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:: EBS Racing :: Do You Know The Benefits Of An Underdrive Pulley?

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Old 02-23-2017, 06:07 PM
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jon@ebsracing.com
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Default :: EBS Racing :: Do You Know The Benefits Of An Underdrive Pulley?







Porsche left some performance on the table when they built the M96 engine in your sports car. With a large diameter crankshaft pulley, your engine is constantly working overtime to spin the air conditioning compressor, alternator, water pump, and power steering pump to higher speeds than they really require. Each of these accessories requires horsepower to spin them, and if you could slow them down, even a little, your engine would be able to send that power to the drive wheels instead. With an EBS Racing 'underdrive' crankshaft pulley, you can do just that.

Possibly the simplest way to free up some horsepower from your Porsche's watercooled flat six engine is by 'underdriving' your engine's accessories. Wether for street or track use, you'll notice an improvement in throttle response, and your engine will rev more freely with this simple modification. This smaller diameter crankshaft pulley fits in place of the larger factory unit with zero further modifications necessary, and comes with the correctly sized belt you'll need. This is a simple modification that you can do at home, or drop off to your favorite independent Porsche shop to have this task completed easily.

If you are planning to take your Porsche to the track, or if you frequently visit the upper limits of your engine's rev range, this underdrive pulley can also prevent your air conditioning pump or power steering pump from being spun too quickly, preventing undue stress and wear. The power steering pump is particularly vulnerable to such issues, and can develop an expensive leak from being spun too quickly. The cost of this pulley and belt is far less than the cost of replacing your steering pump, you can trust us on that one.

The pulley itself is precision machined from aircraft-grade aluminum to have the correct metric-style v-belt grooves. Lightweight aluminum construction of the pulley saves rotational mass over the OEM piece, giving back even more lost power. The pulley also features a beautiful black anodized finish to not only make your engine look better, but also to protect against corrosion to keep it looking that way for decades. We're so sure of the quality of this pulley that it's also been given a 2-year manufacturer warranty, so you can rest easy knowing this is top quality.

This underdrive pully is guaranteed to work with any M96-powered Porsche Boxster, Cayman, or 911 built between 1997 and 2008. This product is not compatible with Mezger engined cars (911 Turbo, GT3, or GT2) or 9A1 engined cars (Direct Fuel Injection engines from 2008 onward). For more information on product benefits or fitment, or to place an order, call one of our EBS Racing Porsche specialists at 1-800-462-3774. To see more photographs or to process your order online, you can visit the product page here.


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Old 02-23-2017, 06:29 PM
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There was some talk about making these underdrive pulleys solid. What problems can arise from this Pulley not being solid?

Also, Has anyone felt the power difference before and after? Any Dyno results of the power?
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Old 02-23-2017, 06:35 PM
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Schnell Gelb
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And do they allow the TDC locking pin to function/need to hack off the boss to lock at tdc ?
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Old 02-23-2017, 06:39 PM
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JayG
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I know it has been discussed before.
To have the info in this thread, what is the downside to having the underdrive pulley?
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Old 02-23-2017, 06:43 PM
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Ahsai
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Downside is lower charging voltage depending on how healthy your charging system was to begin with.

Very appealing upside for sure.
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Old 02-23-2017, 06:53 PM
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Originally Posted by Ahsai
Downside is lower charging voltage depending on how healthy your charging system was to begin with.

Very appealing upside for sure.

Apparently Jake fits them to all his engines so I assume there is a performance advantage but he mentioned before that it was important they were Solid.
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Old 02-23-2017, 07:40 PM
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looks like a decent upgrade for the price
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Old 02-23-2017, 07:47 PM
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Ahsai
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Originally Posted by MoeMonney
Apparently Jake fits them to all his engines so I assume there is a performance advantage but he mentioned before that it was important they were Solid.
Because https://rennlist.com/forums/boxster-...ley-alert.html
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Old 02-23-2017, 07:48 PM
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Originally Posted by Ahsai
Downside is lower charging voltage depending on how healthy your charging system was to begin with.

Very appealing upside for sure.
Thanks Ahsai

Figured it would be good to have pros and cons in the same thread

Does anyone know if you have to modify the timing boss with the EBS pulley?
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Old 02-23-2017, 08:37 PM
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Very interesting....never knew about these...
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Old 02-23-2017, 09:40 PM
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I ran one on the 986 the whole time I had it; I removed it from the 996 after 2-3 years. The combination of the alternator drop due to the UD pulley plus my LED taillights was making my ABS and PSM idiot lights come on every now and then. I'd already sold or given away one of my stock tails, so getting rid of the lights wasn't really an option, and I really didn't want to leave the car in a condition where my wife might be driving when the ABS/PSM went on the blink.

Since removing the UD pulley, I have seen the ABS/PSM once more - when my last battery failed.

If not for this situation, I would have gladly kept the pulley - there is a noticeable positive difference when you underdrive the accessories...
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Old 02-23-2017, 10:08 PM
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Originally Posted by JayG
Thanks Ahsai

Figured it would be good to have pros and cons in the same thread

Does anyone know if you have to modify the timing boss with the EBS pulley?
My guess is most likely as the timing boss is at that 2" radius (same radius as these UD pulleys).
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Old 02-24-2017, 02:37 PM
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Originally Posted by MoeMonney
Apparently Jake fits them to all his engines so I assume there is a performance advantage but he mentioned before that it was important they were Solid.
It's important to know what grade of aluminum is being used. I'm not sure who the manufacturer was of the cracked pulley in the linked thread, but it is surely not ours. We've been using this pulley for years with no quality issues.

As mentioned before, ours are fully warrantied for two years. We trust and stand behind our products.
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Old 02-24-2017, 02:54 PM
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I've had an UD pulley for the past 6 months and 8 or so track days. No complaints.

You'll need to machine/grind a piece off the block for clearance.

Was hard to tell how much impact this had directly because of the many other parts that were installed at the same time (LWFW, LSD, etc).

Car revs insanely quickly now.
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Old 02-24-2017, 03:07 PM
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Yes, the throttle response with the underdrive pulley was one of the best things about it.
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